Need some help planning a childrens mountain bike race - stat!!!

I volunteered to help plan and run a mountain bike race that's on June 11th. We've got the experienced/older rider course (out and back) planned already, but today tried working on the younger riders route.

We've got a small loop (.4 miles) that's mostly flat (we were thinking of running 2 or 3 laps for the youngest kids). Then a figure 8 loop that's .7 miles (thinking 2 or 3 laps as well for the middle kids).

That all seems awfully short distances. I've never done a kids race before...so if anyone has any advice or websites they know of, please share!

The last two seasons I've helped with the kids portion of our local, Tour da Woods race. (See tourdawoods.org). I forget what the exact age ranges are, but here's what we do:

* Youngest group takes one lap on a one-mile loop.
* Next group up takes two laps around the same loop.
* Oldest age group takes a different, five-mile loop.

We make use of some ski trails that are used for skate-skiing in winter. The experience is more like riding a double-track logging trail. Singletrack would be nice, but we have to make do with what we have in the area to work with.

* We let parents ride w/their kids. Some will do that in the very youngest age class.

* We have at least one sweeper, and often several. Our five-mile race could actually benefit from having two sweeps: one to stay up with the group of kids who are actually trying to make some speed, and another to sit behind the inevitable slow group that is just sort of out for the ride. That race almost always devolves into a fast pack and a slow pack.

* Mark the trails well. Our ski trail system has a lot of intersecting trails. We mark the race route. Even so, often an adult will ride ahead to stand at key intersections and make sure that all the kids really do go the right way. We don't want to lose any of them.